LOWELL, Mass. – With less than 48 hours until Election Day, the race for U.S. Senate in Massachusetts between Republican incumbent Scott Brown and Democratic challenger Elizabeth Warren is extremely close, according to a new UMass Lowell-Boston Herald poll released today.

The independent, nonpartisan poll – which surveyed 956 Massachusetts registered voters, 800 of which were deemed likely voters, between Wednesday, Oct. 31 and Saturday, Nov. 3 – found that Brown has a 1 percent lead over Warren among likely voters, with 49 percent for Brown and 48 percent for Warren (with a margin of error of plus or minus 4.1 percentage points). Warren has a 2 percent advantage over Brown among registered voters, with 49 percent for Warren and 47 percent for Brown (with a margin of error of plus or minus 3.7 percentage points).

“Elizabeth Warren now leads among registered voters, but Brown holds a one-point edge among likely voters. What these campaigns do on the ground to get out the vote is likely to determine the winner,” said Joshua Dyck, associate professor of political science and co-director of the UMass Lowell Center for Public Opinion.

Dyck said that the UMass Lowell-Boston Herald poll uses a sophisticated seven-item turnout scale to determine likely voters by assessing whether or not a registered voter has voted in the past, if they know where to vote, and if they indicate that they will definitely vote.

In the last UMass Lowell-Boston Herald poll on the Senate race, which was released Sept. 19, Brown had 49 percent support among likely voters and 45 percent were for Warren. Among registered voters, Brown had 50 percent and Warren had 44 percent.

The poll released today is the fourth by the UMass Lowell Center for Public Opinion and the Boston Herald; they were the first to ask voters about a potential Brown-Warren matchup in conjunction with the first debate in the Senate race between the Democratic candidates in October 2011. UMass Lowell and the Herald hosted one of three debates between Brown and Warren last month; the Oct. 1 event at the Tsongas Center at UMass Lowell, moderated by David Gregory of “Meet the Press,” drew a crowd of more than 4,500 people.

The new poll also found that Brown’s approval rating has decreased slightly to 53 percent from 58 percent in September. His favorability rating is 54 percent, also down from September, when it was 57 percent. Warren’s favorability is up two points to 50 percent from 48 percent in September. Both candidates have seen their unfavorable ratings increase: up from 29 percent in September to 39 percent now for Brown and up from 34 percent in September to 42 percent for Warren.

“The approval numbers for both Brown and Warren have remained relatively steady, but both saw large increases in registered voters’ views of them as unfavorable. This has been a spirited, but very negative campaign, and the high unfavorables lend credence to the suggestion that turnout may be down on Tuesday,” said Dyck.

Looking at the race for the White House, the survey showed that President Barack Obama’s lead over Gov. Mitt Romney remains strong in Massachusetts: 57 percent of likely voters favor Obama over 37 percent for Romney and among registered voters, 59 percent were for Obama and 35 percent for Romney. In the September UMass Lowell-Boston Herald poll, Obama had 59 percent support among likely voters and 60 percent among registered voters, compared to 36 percent of likely voters and 35 percent of registered voters for Romney. In 2008, Obama won 62 percent of the vote in Massachusetts over Republican Sen. John McCain, so Obama’s margin in 2012 is down slightly, consistent with the close national race, according to Dyck.

Other findings from the poll released today include:

The number of voters who are undecided or could change their minds is down to 16 percent from 36 percent in September.

Fifty-five percent of Massachusetts registered voters said Warren will do a better job on issues seen as especially important to women, compared to 35 percent who felt Brown would do a better job. Brown’s lead among male voters has decreased from 20 percent in September to 3 percent. Warren’s 7 percent lead among women is unchanged.

Asked who would do a better job of looking out for middle-class families, 47 percent of registered voters polled said Warren and 43 percent said Brown.

Thirty-seven percent of those polled said Warren is too liberal, up from 30 percent in September. Thirty percent said Brown is too conservative, up from 24 percent in September.

Warren leads Brown among voters between ages 18 and 34, with 54 percent support to Brown’s 45 percent support. Brown leads among voters age 35 to 64, with 50 percent to Warren’s 46 percent, and Warren leads with voters age 65 and older, 51 percent to 46 percent for Brown. The leads in all three age groups are unchanged from September.

Results for the UMass Lowell-Boston Herald poll are based on telephone interviews with a random sample of 956 Massachusetts voters conducted via landline and cellular telephones by Princeton Survey Research Associates International. The poll was directed by independent survey researcher Mike Mokrzycki, the former head of polling for the Associated Press whose other clients include NBC News, where he manages the exit poll operation, and the Pew Research Center. Statistical results are weighted to correct known demographic discrepancies. More information on the poll methodology and full polling data will be available at www.uml.edu/polls.

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